The Winklevoss twins are Bitcoin bulls

The Winklevoss brothers' legal battle with Facebook (FB ) over the social network's messy creation made them rich . They eventually walked away with stock worth around $150 million at today's share price. (They haven't disclosed how much of the stock they're still holding.) A few months ago, word spread that the twins, Cameron and Tyler, had set up their own investment firm and decided to focus on a curious market niche: bitcoins. The brothers are betting that the cyber currency can turn them from millionaires into billionaires. They've invested in buying the coins directly (they told the New York Times that they began "dabbling" last summer , when prices were in the single digits), and this week, they disclosed their first Bitcoin venture investment: A stake in New York-based payment processor BitInstant . The Winklevii, as they're known around town, gave a keynote talk F...